Solar heaters of various designs have been operated for many years. A typical solar energy device comprises a flat plate collector utilizing a series of black coated tubes under a glass faced enclosure to heat water running through the tubes. Such units must be inclined for maximum efficiency to an angle dependent upon the latitude of their use. They are generally placed facing approximately true south. Such an orientation is a compromise between the ideal orientation for the morning and afternoon hours. Therefore, the unit is operating at less than peak efficiency at all but the mid-day hours. Further, such a unit is inefficient in heating air. Therefore, where hot air heating is to be employed in the heated building, a heat exchanger must be provided for transferring heat from the water to air. When utilized on homes having a south facing roof of approximately the right inclination, such units are merely bolted to the roof surface. However, for buildings with flat or gradually sloping roofs, the units must be held at the proper inclination by racks or other structures.
Solar energy devices that track the sun have been devised. In a typical tracking device, a photosensor detects the orientation of the sun and commands a motor to rotate and elevate the platform holding the solar energy device in such a manner that a perfect sun orientation is constantly maintained. Tracking devices are relatively complicated and expensive. Since the entire solar energy device must be mounted for movement, they are limited in their application to light weight solar energy devices that concentrate the sun's rays such as by a parabolic mirror.
Therefore, it is desirable to have a solar energy device that is adaptable to utilizing air as the working fluid and that maintains an effective portion of the solar energy device in sun facing relationship during a high percentage of the day light hours. Such a solar heater is particularly desirable where it is adaptable to solar heaters on flat roofs.